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Heat management must allow the adjustment of optimal operating temperatures of all components of a vehicle. A comprehensive simulation model (KULI) will contain all components relevant for heat management. This includes heat sources, heat exchangers, fans, etc. Main aspects of the simulation are flow and heat transfer analysis. Not only the engine cooling system can be covered with this simulation tool, also the air-conditioning circuit including phase changing models is a part of it (KULI AC). To fulfill the needs of integrating various software tools to an overall simulation cluster an interface to a fluid flow 1-dimensional software (FLOWMASTER) was developed. The use of 1- dimensional methods and mesh flow theory for modeling the underhood air flow of vehicles is very efficient method. For complex flow patterns however it is desirable to use CFD analysis.

A comprehensive simulation method is presented for the optimization of vehicle warm-up. Sophisticated one dimensional simulation methods based on network theory are used for flow simulation to limit computation time and guarantee high simulation quality. Partial integration of three dimensional flow simulation methods help to improve accuracy. Simulation sub-models for the engine, the HVAC system, and the passenger cabin are combined to simulate the warm-up process of the vehicle. This functionality is implemented in a modern software tool named KULI to support the development engineer as good as possible. Steady state and transient simulation are used to optimize the warm-up behavior.

An efficient air-conditioning system is an important factor for the commercial success of an automotive product, because of the thermal comfort for the passengers being an important incentive for the purchaser. A simulation tool is presented that makes it possible to design and optimize A/C refrigerant circuits together with the engine cooling system in a very early stage of the design process. This tool is based on networks including the enhanced heat exchange theory which also takes into consideration refrigerant phase changes. A graphical user interface and predefined simulation models which are based on the respective geometry of the system components make it easy to create a virtual vehicle for mathematical analysis of the various heat and mass flows. High flexibility and short calculation time together with high accuracy enable the engineer to make efficient investigations.